Vehicle seat structure

ABSTRACT

A vehicle seat ( 1 ) structure ( 10 ) is provided in which at least two structural parts ( 12, 14 ) are connected to each other at least at one contact point (P) by means of ultrasonic welding.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a United States National Phase application ofInternational Application PCT/DE2007/001228 and claims the benefit ofpriority under 35 U.S.C. §119 of German Patent Application DE 10 2006033 156.7 filed Jul. 18, 2006, the entire contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a vehicle seat structure with at least twostructural parts which are connected to one another.

BACKGROUND OF THE INVENTION

Known supporting structures of vehicle seats have structural parts whichare stamped from thin sheet steel and are welded to one another, forexample by means of laser welding.

SUMMARY OF THE INVENTION

An object of the invention is to improve a structure of theaforementioned type.

This object is achieved according to the invention by a structurecomprising a first vehicle seat structural part and a second vehicleseat structural part. The first structural part is connected to thesecond vehicle seat structural part by means of ultrasonic welding at acontact point to provide an ultrasonically formed weld connection at thecontact point.

Vehicle seat structures are intended, on the one hand, to comprisematerials having a high degree of weight-specific rigidity, strength andenergy absorption, in order to increase the safety of the passenger and,on the other hand, to use lightweight materials in order to reduce theoverall weight. The manufacture of structures which are optimized interms of load and weight is achieved by combining different materials,i.e. hybrid structures are produced.

The two materials of the hybrid structure may be connected to oneanother. Bonding, riveting, screwing, clinch riveting and welding, forexample, are considered as connection techniques. Welding two metals maytake place without pressure (melt welding), for example in metal activegas welding or in laser welding, by means of which in structures made ofsteel it is possible that the cost and the weight are optimized, or thewelding may be carried out by using pressure (pressure welding), forexample in roll seam welding, projection welding, spot weldingor—according to the invention—ultrasonic welding. In ultrasonic welding,the parts are connected to one another in the plastic but unmeltedstate.

The advantages of ultrasonic welding relative to other welding methodsare that no weld spatter occurs, a connection of aluminum/aluminumalloys and steel and/or (glass) fiber-reinforced plastics is possible,there is a lower heat input and thus less distortion occurs, multiplespot welding is possible and thus shorter process times occur, noholding time is necessary for curing, no welding gap is present as aresult of the method, the process monitoring is easy and the geometry ofthe welded connection may be designed to be load-compatible.

As at least two of the structural parts consist of different materialsand are connected to one another by means of ultrasonic welding at leastone contact point, a low-weight hybrid structure is provided which isproduced cost-effectively and which provides the necessary strength. Thematerials may thus, on the one hand, be aluminum/aluminum alloys and, onthe other hand, steel. However, other materials are also possible, forexample glass fiber-reinforced plastics, or other fiber-reinforcedplastics, for example in combination with one of the aforementionedmetals. Two or more structural parts may be simultaneously connected toone another. The simultaneous connection at a plurality of contactpoints is possible, for example by means of a plurality of, possiblydifferent, sonotrodes of an ultrasonic welding device.

The structure is preferably the supporting structure of a seat-back of avehicle seat, but may also be the supporting structure of a seat part.Preferably, base sheets and side members are connected to one another.For example, side parts and cross members could also be connected to oneanother.

The invention is described in more detail hereinafter with reference toan embodiment with a modification shown in the drawings. The variousfeatures of novelty which characterize the invention are pointed outwith particularity in the claims annexed to and forming a part of thisdisclosure. For a better understanding of the invention, its operatingadvantages and specific objects attained by its uses, reference is madeto the accompanying drawings and descriptive matter in which preferredembodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of an embodiment according to theinvention;

FIG. 2 is a schematic side view of a vehicle seat including theembodiment according to the invention;

FIG. 3 is a sectional view through the embodiment along the line III-IIIin FIG. 1;

FIG. 4 is a sectional view through a modification of the embodiment ofFIG. 1;

FIG. 5 is a partially sectioned and schematic view of a known ultrasonicwelding device;

FIG. 6 is a schematic partial view of the ultrasonic welding device witha tilted sonotrode and corresponding workpieces;

FIG. 7 is a further schematic partial view corresponding an embodimentof the workpieces;

FIG. 8 is a schematic partial view of the ultrasonic welding device withsonotrodes arranged alternately;

FIG. 9 is a side view of device shown in FIG. 8; and

FIG. 10 is a perspective partial view of the ultrasonic welding devicewith sonotrodes of different types arranged offset relative to oneanother.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in particular, FIG. 2, a vehicle seat 1 of amotor vehicle has a seat part 3, which is connected to the vehiclestructure S of the motor vehicle, and a seat-back 6 which is pivotablerelative to the seat part 3, which is articulated on both sides on theseat part 3. To use the seat, the seat-back 6 is locked to the seat part3 or to the vehicle structure S. In the embodiment, the vehicle seat 1is a rear seat system with a split backrest, i.e. the seat-back 6 is onethird or two thirds of the aforementioned split backrest.

The seat-back 6 has a supporting structure 10 which comprises asstructural parts a base sheet 12 and at least one side member 14. Thebase sheet 12 is substantially planar. It may comprise beads for thereinforcement thereof. The side member 14 has a substantially U-shapedprofile. In the present case, a plurality of side members 14 areconnected together to form a peripheral frame, partially also formedintegrally relative to one another. The present side members 14 arearranged on the front face of the base sheet 12—facing the occupant whenthe seat is used—and connected thereto—by forming box sections. Thestructure 10 thus formed is also upholstered on the front face of thebase sheet 12. The rear face of the base sheet 12 directly faces theluggage compartment, possibly simply painted or covered, and may extendthe loading floor when the seat-back 4 is pivoted forward.

In the embodiment, the base sheet 12 consists of aluminum, morespecifically in the present case of aluminum sheet Al Mg 4.5 Mn, at athickness of for example 0.7 mm or 1.0 mm. In the embodiment, the sidemember 14 consists of steel, more specifically in the present case sheetsteel at a thickness of 0.7 mm. The side member 14 and the base sheet 12are ultrasonically welded to one another, i.e. connected by means ofultrasonic welding.

An ultrasonic welding device 100 known per se, has an anvil 101 (baseplate), an upright 103 fixed relative to the anvil 101 and a slide 105which is movable, in the present case vertically movable, relative tothe upright 103. The slide 105 comprises a guide and receiver for afeeder unit 111 which is mounted movably, in particular parallel,relative to the slide 105 in the guide and receiver of the slide 105.The feeder unit 111 is thus movable relative to the anvil 101. Thefeeder unit 111 is acted upon by a pneumatic cylinder 113 supported onthe slide 105, the piston 115 thereof acting by means of a piston rod116 and a damping member 117, as well as a force transducer 119 inseries, on the feeder unit 111, in the present case on the upper facethereof. A restoring spring 121 pretensions the feeder unit 111 in thedirection of the pneumatic cylinder 113.

The feeder unit 111 encompasses a converter 125 which converts a highvoltage generated by a generator 127 into ultrasound. The ultrasound istransmitted by a booster 129 to one or more sonotrodes 131 at the tip ofthe feeder unit 111, i.e. in the present case on the underside thereof.The sonotrodes 131 are positioned on the one workpiece, the otherworkpiece bearing against the anvil 101, i.e. the workpieces beingarranged between the sonotrodes 131 and the anvil 101. The pneumaticcylinder 113 creates a static pressure, so that the two workpieces bearagainst one another under pretension at the contact points P, monitoredand controlled by the force transducer 119.

The ultrasound introduced via the sonotrodes 131 into the upperworkpiece, heats the materials (steel/aluminum) at the pretensionedcontact points P to approximately 300°-400° C. With this physicalcontact an atomic interaction is produced between the materials,aluminum atoms diffusing into the steel surface.

By means of such an ultrasonic welding device 100 the side member 14 iswelded to the base sheet 12. The welded connection is arranged in itssize and contour such that, relative to its strength, the requiredenergy absorption of the structure 10 is ensured. For reducing theprocessing times, a plurality of sonotrodes 131 simultaneously weld aplurality of contact points P positioned in one plane, between the sidemember 14 and the base sheet 12. In a modified embodiment, it is alsopossible to weld simultaneously two interlocking side members 14 ofdifferent profiles to the base sheet 12, i.e. to carry out a tripleweld. The sonotrodes 131 may vary in their dimensioning and/orconstruction (type). The welded seam may be dimensioned differentlydepending on the loads to be received, which also may be achieved by thedifferent sonotrodes 131. The possible basic shapes of the weldedsurfaces at the contact points P may, in particular, be annular, squareor circular. According to requirements, a plurality of feeder units 111and/or a plurality of slides 105 may also be provided.

According to the design of the ultrasonic welding device 100, wheninserting the workpieces, the upright 103 may act as a limit for thebase sheet 12, i.e. define the maximum possible distance from onecontact point P to the edge of the base sheet 12. So as to reach alsoregions in the center of the base sheet 12, the sonotrode 131 may betilted, i.e. relative to the upright 103 and to the direction ofmovement of the slide 105. Preferably, the entire feeder unit 111 istilted relative to the direction of movement of the slide 105.Accordingly, the anvil 101 and the workpieces are adapted thereto. Aregion of the anvil 101 is tilted at the same angle. The side member 14has a correspondingly bent-back welding flange 14 a and the base sheet12 is correspondingly formed. FIG. 6 shows a partial view of a thusmodified ultrasonic welding device 100. Depending on the spatialrelationships, it may be expedient to allow the welding flange 14 a toproject from the side member 14 not at an obtuse angle as in FIG. 6 butat an acute angle, as shown in FIG. 7. An alternate arrangement of thesetwo concepts is also possible along an axis perpendicular to the drawingplane.

In order to reduce the distance between two contact points P, it isadvantageous to supply the associated sonotrodes 131 alternately fromdifferent sides relative to the plane through the contact points P, forexample alternately from above and from below, as shown in FIG. 8 andalso in side view in FIG. 9. The anvil 101 has correspondinglyalternately arranged regions. Some of the sonotrodes 131 and regions ofthe anvil 101 are thus connected to the feeder unit 111, the others arefixed. A combination is also possible with the tilted sonotrodes 131according to FIGS. 6 and/or 7.

In FIG. 10 it is shown how a plurality of sonotrodes 131 of differenttypes are arranged offset by 90° relative to one another. In this case,two sonotrodes 131 of the “torsion sonotrode” type are shown whichrotate during welding about their longitudinal axis and in the presentcase have two (for example cam-like) active surfaces 131 a on the frontface. These two sonotrodes 131 are positioned with their longitudinalaxis perpendicular to the plane of the base sheet 12. Moreover, threesonotrodes 131 of the “linear lambda sonotrode” type are shown, whichduring welding are displaced in a linear manner perpendicular to theirlongitudinal axis, and in the present case have four (for examplecam-like) active surfaces 131 a in the radial direction, of whichhowever only two are in use at the same time (the other two activesurfaces serve as a back-up in case of wear). These three sonotrodes 131are arranged (with frame support) in a plane parallel to the base sheet12 and move within this plane perpendicular to their longitudinal axis.Viewed along the side member 14, one of the three sonotrodes 131 of the“linear lambda sonotrode” type is arranged between the two sonotrodes131 of the “torsion sonotrode” type, and this group of three is arrangedbetween the two other sonotrodes 131 of the “linear lambda sonotrode”type. The directions of movement of the sonotrodes 131 are indicated byarrows in FIG. 10. By means of the five sonotrodes 131 with the twoactive surfaces 131 a, which are present during use, ten welding pointsmay be produced simultaneously (and at close intervals). Preferably, theintervals between the five sonotrodes 131 are the same, so that fiveevenly spaced-apart pairs of two respective welding points are producedat the ten contact points P.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

1. A vehicle seat structure comprising: a first vehicle seat structuralpart; a second vehicle seat structural part, said first vehicle seatstructural part being connected to said second vehicle seat structuralpart by means of ultrasonic welding at a contact point to provide anultrasonically formed weld connection at said contact point.
 2. Astructure as claimed in claim 1, wherein said first vehicle seatstructural part and said second vehicle seat structural part consist ofdifferent materials.
 3. A structure as claimed in claim 2, wherein atleast one of said first vehicle seat structural part and said secondvehicle seat structural part consists of aluminum/aluminum alloy and atleast one other of said first vehicle seat structural part and saidsecond vehicle seat structural part consists of steel.
 4. The structureas claimed in claim 2, further comprising: a third vehicle seatstructural part wherein one of said first vehicle seat structural partand said second vehicle seat structural part and said third vehicle seatstructural part is made of aluminum/aluminum alloy and two other of saidfirst vehicle seat structural part and said second vehicle seatstructural part and said third vehicle seat structural part is made ofsteel, with said first vehicle seat structural part and said secondvehicle seat structural part and said third vehicle seat structural partconnected to one another by means of a triple weld at said contact point(P).
 5. The structure as claimed in claim 1, wherein the structure isthe supporting structure of a seat-back of a vehicle seat.
 6. Thestructure as claimed in claim 5, wherein one of said first vehicle seatstructural part and said second vehicle seat structural part is a basesheet and the other of said first vehicle seat structural part and saidsecond vehicle seat structural part is a side member.
 7. The structureas claimed in claim 1, wherein the structural parts are connected to oneanother at a plurality of contact points, said contact points beinglocated in one plane.
 8. (canceled)
 9. A method for connecting at leasttwo structural parts of a supporting structure, the method comprisingthe steps of: providing a first vehicle seat structural part; providinga second vehicle seat structural part; and connecting the two structuralparts to one another at least one contact point by means of ultrasonicwelding.
 10. An ultrasonic welding device, comprising: an anvil; and afeeder unit which is movable relative to the anvil and which may besubjected to a controlled pretensioning; a sonotrode, the workpieces tobe welded being arranged between the anvil and the sonotrode, whereinthe ultrasonic welding device connects together at least two structuralparts of a supporting structure of a motor vehicle seat including afirst vehicle seat structural part and a second vehicle seat structuralpart, at least one contact point by means of ultrasonic welding.
 11. Aultrasonic welding device as claimed in claim 10, further comprising atleast one additional sonotrode wherein a plurality of sonotrodes areprovided in order to connect simultaneously the structural parts to oneanother at a plurality of contact points.
 12. The ultrasonic weldingdevice as claimed in claim 11, wherein relative to a plane through atleast two contact points at least two sonotrodes are arrangedalternately on different sides.
 13. The ultrasonic welding device asclaimed in claim 11, further comprising an upright and a slide connectedto said upright wherein at least one of the sonotrodes and/or the feederunit is tilted relative to the upright and/or the direction of movementof the slide is movable relative to the upright.
 14. The ultrasonicwelding device as claimed in claim 10, further comprising at least oneadditional sonotrode wherein a plurality of sonotrodes of differenttypes are arranged offset by 90° relative to one another.
 15. Theultrasonic welding device as claimed in claim 14, wherein said pluralityof sonotrodes include torsion sonotrodes and linear lambda sonotrodeswherein the torsion sonotrodes and the linear lambda sonotrodes arearranged alternately.
 16. A structure as claimed in claim 2, wherein atleast one of said first vehicle seat structural part and said secondvehicle seat structural part consists of a fiber-reinforced plastic andat least one other of said first vehicle seat structural part and saidsecond vehicle seat structural part consists of steel.
 17. A method asclaimed in claim 9, wherein: said step of connecting includes providingan ultrasonic welding device having an anvil, a feeder unit which ismovable relative to the anvil and which may be subjected to a controlledpretensioning, and at least one sonotrode whereby the workpieces to bewelded are arranged between the anvil and the sonotrode and wherein theultrasonic welding device connects together the first vehicle seatstructural part and the second vehicle seat structural part at the atleast one contact point by means of ultrasonic welding.
 18. A method asclaimed in claim 17, wherein the ultrasonic welding device furthercomprises at least one additional sonotrode wherein a plurality ofsonotrodes are provided and act to simultaneously connect the structuralparts to one another at a plurality of contact points.
 19. A method asclaimed in claim 17, wherein relative to a plane through at least twocontact points at least two sonotrodes are arranged alternately ondifferent sides.
 20. A method as claimed in claim 17, wherein theultrasonic welding device further comprises an upright and a slideconnected to said upright wherein at least one of the sonotrodes and/orthe feeder unit is tilted relative to the upright and/or the directionof movement of the slide which is moved relative to the upright.
 21. Amethod as claimed in claim 17, wherein the ultrasonic welding devicefurther comprises at least one additional sonotrode wherein a pluralityof sonotrodes of different types are arranged offset by 90° relative toone another including torsion sonotrodes and linear lambda sonotrodeswith the torsion sonotrodes and the linear lambda sonotrodes arrangedalternately.